Problem: If $x \dagger y = x+3y$ and $x \oplus y = 2x^{2}-y^{2}$, find $-3 \dagger (-4 \oplus -5)$.
Solution: First, find $-4 \oplus -5$ $ -4 \oplus -5 = 2(-4)^{2}-(-5)^{2}$ $ \hphantom{-4 \oplus -5} = 7$ Now, find $-3 \dagger 7$ $ -3 \dagger 7 = -3+(3)(7)$ $ \hphantom{-3 \dagger 7} = 18$.